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  <script>
    //map 
    //参数：arr.map(item,idex,arr)
    //作用：遍历数组，返回新数组，用于处理数据
    //返回：返回新数组
    
     const arr = [1,2,3]
     const arr1=arr.map(item=>item*2)
     console.log(arr1);//返回新的数组


  </script>
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